Improvement in bridges



@anni @twine CHARLES H. PARKER, 0F BOSTON, MASSAGHUSETTS.

l vLetters Patent No. 98,620, (lated January 4, 1870.

IMPROVEMEN T IN BRIDGES.

The Schedule referred to in these Letters Patent' and making part of the same.

MOH-

To whom itrmay concern Be it known that I, CHARLES H. PARKER, of Boston, in the county of Suffolk, and State of Massachu- 4 setts, have invented certain new and useful Improvements in the Construction of Bridges; and I hereby declare the following to be a full, clear, and exact description of the same, reference being had to the accompanying drawings, in which- Figure 1 is a side elevation of a portion of a bridge embodying my invention.

Figure 2 is a transverse section, representing, on a larger scale, theparts shown in iig. 1.

Ihe present invent-ion relates to the construction of' cantilever-bridges.

'lhe object l have in view is to avail myself', at the same time, both of the great value of wire, as used in 4suspension-bridges, andY of the full value of the decreasing section in the top or tension-member of a cantilever-bridge, (due to the decrease of strains toward the centre ofthe bridge.)

To this eud,.I form theatop, or tension-member, of wire, which is coated or covered in a suitable manner, as is usual in the suspension-system; and, in order to obtain the decreasing section, I carry back, from vsuitable points on the bridge, which are usually the points of connection between the chord and the web, such wiresas are not needed, returning them to the point of fastening at the anchorage, and continuing the chord with a decreased number ot' wires, reducing the section of the chord las it departs from the anchorage, and thus realizing the object I have in view.

It will be seen, therefore, that the main features of my invention`consist, first, in a cantilever-bridge, in

which the tension-member iscomposed of wire; and secondly, in the use ofthe wire in the particular manner above stated. i

The construction and arrangement of the devices, by which these results may be accomplished, can be varied greatly, but I much prefer the use of those herein specified. l

The top or tension-member of the bridge is shown at A, composed of a suitable .number of wires, all of which are fastened at the point of anchorage a.

In order to eiect the gradual reduction in the section of the chord, as specified, I have devised the following mode of fastening at each point of connection, b, of the top member with the web, or that portion of the cantilever' between the top and bottom members.

Iemploy, ateach of these points of connection, a cross, B, shown clearly in g. 2, which is bound into and securely retained by the wires forming the chord.

Starting from the point o f anchorage, I am enabled to reduce the section ofthe chord, by passing by each cross with such a number of wires as is required to give suicient section in the succeeding panel or baf, while the wires, in excess of this number, are passed around/one of the arms of the cross, and returned to the point of fastening at the anchorage. Thus, the number of wires required to form the last panel, at the' centre ofthe bridge, is passed around the last cross, and thence is continuous to the point of anchorage, andthe wires in each preceding panel or bay are also continuons to the same point, but more in number as the strains increase toward the point of support upon theshore.

As before stated, the whole chord is to be wound or covered,- as is usual inthe suspension-system; and, at the points of connection, I employ a covering or holding-plate, O, which surrounds `the wire, and through which the arms of the cross pass.`

Nuts, on the ends of the cross, hold the parts rmly together, while the plate is bolted, or otherwise suitably secured to the post, as seen in g. 2.

Any other suitable fastening may be made to these plates,- and the diagonal rods of the web may be made to take hold ofthe ends of the cross, as shown iniig. 2.

As I have above stated, it is manifest thata variety of devices, other than those herein shown, may be employed to effect the same results, and I do not, therefore, limit my claim to the precise details specified;

but

What I claim, and desire to secure by Letters Patent is- 17. A cantilever-bridge, in which the tension-member is constructed of wire, substantially as set forth.

2. llhe use of wire in the cantilever-bridge, in the manner and for thepurposes speciiied.

3. The cross B, or its equivalent, when used in the manner andfor the purposes set forth.

4. The holding-plate, or its equivalent, :for surrounding the chord, and receiving the arms of the cross, at the points ofjunction of the chord with the web, substantially as shown and described.

5. The combination of the wire rope, the holdingplate, andthe cross, when used in the manner and for the purposes set forth. i

In testimony whereof, I have signed my naine to this specification, before two subscribing witnesses.

GHAS. H. PARKER.

lVitnesses g WM. A. BLODGETT, CADWALLADER GURRY. 

